Wireless communication systems are known to support wireless communications between wireless communication devices affiliated with the system. Such wireless communication systems range from national and/or international cellular telephone systems to point-to-point in-home wireless networks. Each type of wireless communication system is constructed, and hence operates, in accordance with one or more standards. Such wireless communication standards include, but are not limited to IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), wireless application protocols (WAP), local multi-point distribution services (LMDS), multi-channel multi-point distribution systems (MMDS), and/or variations thereof.
An IEEE 802.11 compliant wireless communication system includes a plurality of wireless communication devices (e.g., laptops, personal computers, personal digital assistants, et cetera coupled to a station) and may further include a plurality of access points. If the IEEE 802.11 wireless communication system does not include access points, then the wireless communication devices employ an independent basic service set (IBSS) to facilitate point-to-point communications. If the IEEE 802.11 wireless communication system includes access points, the access points provide a basic service set (BSS) for wireless communication devices within the coverage area of the access points. For both IBSS and BSS type of communications, the transmitting device (e.g., a station or access point) transmits at a fixed power level regardless of the distance between the transmitting device and a targeted device (e.g., station or access point). Typically, the closer the transmitting device is to the targeted device, the less error there will be in the reception of the transmitted signal. However, as is generally understood in the art, wireless transmissions may include some error and still provide an accurate transmission. Thus, transmitting at power levels that provide too few errors is energy inefficient.
As is also generally understood in the art, transmissions by one wireless communication device interfere to some degree with transmissions of other wireless communication devices. The level of interference is dependent, at least in part, on the transmit power of the interfering device or devices. Accordingly, cell patterns are employed by wireless communication systems to minimize interference from BSS to BSS, however, some adjacent channel interference may still be present.
Therefore, a need exists for a method and apparatus that adjusts transmit power of wireless communication devices to improve power efficiency, to reduce interference, and/or to meet regulatory requirements.